New insights about surface, structure of asteroid Bennu

When NASA's OSIRIS-REx spacecraft collected samples from asteroid Bennu's surface in 2020, forces measured during the interaction provided scientists with a direct test of the poorly understood near-subsurface physical properties of rubble-pile asteroids. Now, a Southwest Research Institute-led study has characterized the layer just below the asteroid's surface as composed of weakly bound rock fragments containing twice the void space as the overall asteroid.

"The low gravity of rubble-pile asteroids such as Bennu weakens its near-subsurface by not compressing the upper layers, minimizing the influence of particle cohesion," said SwRI's Dr. Kevin Walsh, lead author of a paper about this research published in the journal Science Advances. "We conclude that a low density, weakly bound subsurface layer should be a global property of Bennu, not just localized to the contact point."

Fitting its designation as a "rubble-pile asteroid," Bennu is a spheroidal collection of rock fragments and debris 1,700 feet in diameter and held together by gravity. It is thought to have been formed after a collision involving a larger main-asteroid-belt object. Rocks are scattered across its heavily cratered surface, indicating that it has had a rough-and-tumble existence since being liberated from its much larger parent asteroid some millions or billions of years ago.

The goal of OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) mission is to collect and return at least 60 grams of surface material from Bennu and deliver it to Earth in 2023. Sample collection activities provided additional insights.

According to Walsh, researchers involved in the OSIRIS-REx mission have so far measured Bennu's thermal properties and craters to estimate the strength and porosity of discrete particles of rubble-pile asteroids. The ensemble of particles, or regolith, at an asteroid's surface controlling and influencing long-term evolution have not yet been probed directly until now.

Before, during, and after the sampling event, the Sample Acquisition Verification Camera (SamCam) of the OSIRIS-REx Camera Suite captured images looking at the Touch-and-Go Sample Acquisition Mechanism (TAGSAM) robotic arm.

"The SamCam images bracketing the moment of contact show the contact caused considerable disturbance at the sample site," said Dr. Ron Ballouz, a co-author from Johns Hopkins University's Applied Physics Laboratory. "Nearly every visible particle is moved or re-oriented at all points along the circumference of TAGSAM up to a 15-inch radius."

These SamCam images showed the downward force of TAGSAM lifted a nearly 16-inch rock. Though strong enough to withstand breaking, the rock was re-oriented and small debris lofted off its surface. The mobility of these millimeter-scale particles under relatively weak forces suggests minimal cohesive bonding with the surface of the larger rock.

Scientists have theorized that the average regolith particle size increases as asteroid size decreases, because larger bodies retain smaller materials due to a higher surface gravity. The team then compared Bennu to similar rubble-pile asteroids.

"We discovered a dichotomy between the rough, boulder-covered surfaces of Bennu and Ryugu versus Itokawa, which includes ponds of smaller particles across 20% of its surface," Walsh said. "This could have several explanations, including that the latter's near-surface has compressed enough to frustrate these microparticles percolating into the interior or perhaps the granular deposits are subsurface layers revealed by a recent disruptive reorganization of the body."

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Ozone depletion over North Pole produces weather anomalies

Many people are familiar with the hole in the ozone layer over Antarctica, but what is less well known is that occasionally, the protective ozone in the stratosphere over the Arctic is destroyed as well, thinning the ozone layer there. This last happened in the spring months of 2020, and before that, in the spring of 2011.

Each time the ozone layer has been thinned out, climate researchers subsequently observed weather anomalies across the entire northern hemisphere. In central and northern Europe, Russia and especially in Siberia, those spring seasons were exceptionally warm and dry. In other areas, such as polar regions, however, wet conditions prevailed. These weather anomalies were particularly pronounced in 2020. Switzerland was also unusually warm and dry that spring.

Whether there is a causal relationship between stratospheric ozone destruction and the observed weather anomalies is a matter of debate in climate research. The polar vortex in the stratosphere, which forms in winter and decays in spring, also plays a role. Scientists who have studied the phenomenon so far have arrived at contradictory results and different conclusions.

New findings are now shedding light on the situation, thanks to doctoral student Marina Friedel and Swiss National Science Foundation Ambizione Fellow Gabriel Chiodo. Both are members of the group headed by Thomas Peter, Professor of Atmospheric Chemistry at ETH Zurich, and are collaborating with Princeton University and other institutions.

Simulations reveal correlation

To uncover a possible causal relationship, the researchers ran simulations that integrated ozone depletion into two different climate models. Most climate models consider only physical factors, not variations in stratospheric ozone levels, in part because this would require much more computing power.

But the new calculations make it clear: the cause of the weather anomalies observed in the northern hemisphere in 2011 and 2020 is mostly ozone depletion over the Arctic. The simulations the researchers ran with the two models largely coincided with observational data from those two years, as well as eight other such events that were used for comparison purposes. However, when the scientists "turned off" ozone destruction in the models, they could not reproduce those results.

"What surprised us most from a scientific point of view is that, even though the models we were using for the simulation are utterly different, they produced similar results," says co-author Gabriel Chiodo, SNSF Ambizione Fellow at the Institute for Atmospheric and Climate Science.

The mechanism explained

The phenomenon as the researchers have now studied it begins with ozone depletion in the stratosphere. For ozone to be broken down there, temperatures in the Arctic must be very low. "Ozone destruction occurs only when it is cold enough and the polar vortex is strong in the stratosphere, about 30 to 50 kilometres above the ground," Friedel points out.

Normally, ozone absorbs UV radiation emitted by the sun, thereby warming the stratosphere and helping to break down the polar vortex in spring. But if there is less ozone, the stratosphere cools and the vortex becomes stronger. "A strong polar vortex then produces the effects observed at the Earth's surface," Chiodo says. Ozone thus plays a major role in temperature and circulation changes around the North Pole.

Greater accuracy possible for long-term forecasts

The new findings could help climate researchers make more accurate seasonal weather and climate forecasts in future. This allows for better prediction of heat and temperature changes, "which is important for agriculture," Chiodo says.

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Gestures can improve understanding in language disorders

When words fail, gestures can help to get the message across -- especially for people who have a language disorder. An international research team has now shown that listeners attend the gestures of people with aphasia more often and for much longer than previously thought. This has implications for the use of gestures in speech therapy.

People who suffer from an acquired language disorder due to a brain injury -- for example after a stroke, traumatic brain injury or brain tumor -- often have difficulties communicating with others. Previous research on aphasia indicates that these patients often try to express their needs using hand gestures. It was previously assumed that conversation partners pay relatively little attention to such non-verbal forms of communication -- but this assumption was based on research involving participants without language disorders.

Communicating with gestures

A new study from the University of Zurich, carried out together with researchers from the Netherlands and Japan, looked at whether gestures receive more attention if the verbal communication is impeded by aphasia. The researchers showed healthy volunteers video clips in which people with and without speech disorders described an accident and a shopping experience. As the participants watched the video clips, their eye movements were recorded.

Focus of attention shifts

"Our results show that when people have very severe speaking difficulties and produce less informative speech, their conversation partner is more likely to pay attention to their hand movements and to look longer at their gestures," says Basil Preisig of the Department of Comparative Language Science at UZH. In people who have no limitations in verbal production, hand gestures are granted less attention. Thus, it seems that listeners shift their attention when the speaker has a speech impediment and focus more on the speaker's nonverbal information provided through gestures. "For people with aphasia, it may be worth using gestures more in order to be better understood by the other person," says Preisig.

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The importance of elders

According to long-standing canon in evolutionary biology, natural selection is cruelly selfish, favoring traits that help promote reproductive success. This usually means that the so-called "force" of selection is well equipped to remove harmful mutations that appear during early life and throughout the reproductive years. However, by the age fertility ceases, the story goes that selection becomes blind to what happens to our bodies. After the age of menopause, our cells are more vulnerable to harmful mutations. In the vast majority of animals, this usually means that death follows shortly after fertility ends.

Which puts humans (and some species of whale) in a unique club: animals that continue to live long after their reproductive lives end. How is it that we can live decades in selection's shadow?

"From the perspective of natural selection, long post-menopausal life is a puzzle," said UC Santa Barbara anthropology professor Michael Gurven. In most animals, including chimpanzees -- our closest primate brethren -- this link between fertility and longevity is very pronounced, where survival drops in sync with the ability to reproduce. Meanwhile in humans, women can live for decades after their ability to have children ends. "We don't just gain a few extra years -- we have a true post-reproductive life stage," Gurven said.

In a paper published in the Proceedings of the National Academy of Sciences, senior author Gurven, with former UCSB postdoctoral fellow and population ecologist Raziel Davison, challenge the longstanding view that the force of natural selection in humans must decline to zero once reproduction is complete.

They assert that a long post-reproductive lifespan is not just due to recent advancements in health and medicine. "The potential for long life is part of who we are as humans, an evolved feature of the life course," Gurven said.

The secret to our success? Our grandparents.

"Ideas about the potential value of older adults have been floating around for awhile," Gurven said. "Our paper formalizes those ideas, and asks what the force of selection might be once you take into account the contributions of older adults."

For example, one of the leading ideas for human longevity is called the Grandmother Hypothesis -- the idea that, through their efforts, maternal grandmothers can increase their fitness by helping improve the survival of their grandchildren, thereby enabling their daughters to have more children. Such fitness effects help ensure that the grandmother's DNA is passed down.

"And so that's not reproduction, but it's sort of an indirect reproduction. The ability to pool resources, and not just rely on your own efforts, is a game changer for highly social animals like humans," Davison said.

In their paper, the researchers take the kernel of that idea -- intergenerational transfers, or resource sharing between old and young -- and show that it, too, has played a fundamental role in the force of selection at different ages. Food sharing in non-industrial societies is perhaps the most obvious example.

"It takes up to two decades from birth before people produce more food than they're consuming," said Gurven, who has studied the economy and demography of the Tsimané and other indigenous groups of South America. A lot of food has to be procured and shared to get kids to the point where they can fend for themselves and be productive group members. Adults fill most of this need with their ability to obtain more food than they need for themselves, a provisioning strategy that has sustained pre-industrial societies for ages and also carries over into industrialized societies.

"In our model, the large surplus that adults produce helps improve the survival and fertility of close kin, and of other group members who reliably share their food, too," Davison said. "Viewed through the lens of food production and its effects, it turns out that the indirect fitness value of adults is also highest among reproductive-aged adults. But using demographic and economic data from multiple hunter-gatherers and horticulturalists, we find that the surplus provided by older adults also generates positive selection for their survival. We calculate all this extra fitness in late adulthood to be worth up to a few extra kids!"

"We show that elders are valuable, but only up to a point," contends Gurven. "Not all grandmothers are worth their weight. By about their mid-seventies, hunter-gatherers and farmers end up soaking up more resources than they provide. Plus, by their mid-seventies, most of their grandkids won't be dependents anymore, and so the circle of close kin who stand to benefit from their help is small."

But food isn't everything. Beyond getting fed, children are also taught and socialized, trained in relevant skills and worldviews. This is where older adults can make their biggest contributions: While they don't contribute as much to the food surplus, they have the accumulation of a lifetime of skills they can deploy to ease the burden of childcare on parents, as well as knowledge and training that they can pass on to their grandchildren.

"Once you take into account that elders are also actively involved in helping others forage, then it adds even more fitness value to their activity and to them being alive," Gurven said. "Not only do elders contribute to the group, but their usefulness helps ensure that they also receive from the surpluses, protections and care from their group. In other words, interdependence runs both ways, from old to young, and young to old."

"If you're part of my social world, there might be some kickback," Davison explained. "So to the extent that we're interdependent, I'm vested in your interest, beyond just simple kinship. I'm interested in getting you to be as skilled as possible because some of your productivity could help me down the road."

Gurven and Davison found that rather than our long lifespans opening up opportunities that led to a human-like foraging economy and social behavior, the reverse is more likely -- our skills-intensive strategies and long-term investments in the health of the group preceded and evolved with our shift to our particular human life history, with its extended childhood and unusually long post-reproductive stage.

In contrast, chimpanzees -- who represent our best guess as to what humans' last common ancestor may have been like -- are able to forage for themselves by age 5. However, their foraging activities require less skill, and they produce minimal surplus. Even so, the authors show that if a chimpanzee-like ancestor would share their food more widely, they could still generate enough indirect fitness contributions to increase the force of selection in later adulthood.

"What this suggests is that human longevity is really a story about cooperation," said Gurven. "Chimpanzee grandmothers are rarely observed doing anything for their grandkids."

Though the authors say their work is more about how the capacity for long life came to first exist in the Homo lineage, the implication that we owe it to elders everywhere is an important reminder looking forward.

"Despite elders being far more numerous today than ever before in the past, there's still much ageism and underappreciation of older adults," Gurven said. "When COVID seemed to be most deadly just for older adults, many shrugged their shoulders about the urgency of lockdown or other major precautions.

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Porosity of the moon's crust reveals bombardment history

Around 4.4 billion years ago, the early solar system resembled a game of space rock dodgeball, as massive asteroids and comets, and, later, smaller rocks and galactic debris pummeled the moon and other infant terrestrial bodies. This period ended around 3.8 billion years ago. On the moon, this tumultuous time left behind a heavily cratered face, and a cracked and porous crust.

Now MIT scientists have found that the porosity of the moon's crust, reaching well beneath the surface, can reveal a great deal about the moon's history of bombardment.

In a study appearing in Nature Geoscience, the team has shown through simulations that, early on in the bombardment period, the moon was highly porous -- almost one-third as porous as pumice. This high porosity was likely a result of early, massive impacts that shattered much of the crust.

Scientists have assumed that a continuous onslaught of impacts would slowly build up porosity. But surprisingly, the team found that nearly all the moon's porosity formed rapidly with these massive imapcts, and that the continued onslaught by smaller impactors actually compacted its surface. These later, smaller impacts acted instead to squeeze and compact some of the moon's existing cracks and faults.

From their simulations, the researchers also estimated that the moon experienced double the number of impacts as can be seen on the surface. This estimate is lower than what others have assumed.

"Previous estimates put that number much higher, as many as 10 times the impacts as we see on the surface, and we're predicting there were fewer impacts," says study co-author Jason Soderblom, a research scientist in MIT's Department of Earth, Atmospheric and Planetary Sciences (EAPS). "That matters because that limits the total material that impactors like asteroids and comets brought to the moon and terrestrial bodies, and gives constraints on the formation and evolution of planets throughout the solar system."

The study's lead author is EAPS postdoc Ya Huei Huang, along with collaborators at Purdue University and Auburn University.

A porous record

In the team's new study, the researchers looked to trace the moon's changing porosity and use those changes below the surface to estimate the number of impacts that occurred on its surface.

"We know the moon was so bombarded that what we see on the surface is no longer a record of every impact the moon has ever had, because at some point, impacts were erasing previous impacts," Soderblom says. "What we're finding is that the way impacts created porosity in the crust is not destroyed, and that can give us a better constraint on the total number of impacts that the moon was subject to."

To trace the evolution of the moon's porosity, the team looked to measurements taken by NASA's Gravity Recovery and Interior Laboratory, or GRAIL, an MIT-designed mission that launched twin spacecraft around the moon to precisely map the surface gravity.

Researchers have converted the mission's gravity maps into detailed maps of the density of the moon's underlying crust. From these density maps, scientists have also been able to map the current-day porosity throughout the lunar crust. These maps show that regions surrounding the youngest craters are highly porous, while less porous regions surround older craters.

Crater chronology

In their new study, Huang, Soderblom and their colleagues looked to simulate how the moon's porosity changed as it was bombarded with first large and then smaller impacts. They included in their simulation the age, size, and location of the 77 largest craters on the moon's surface, along with GRAIL-derived estimates of each crater's current-day porosity. The simulation includes all known basins, from the oldest to the youngest impact basins on the moon, and span ages between 4.3 billion and 3.8 billion years old.

For their simulations, the team used the youngest craters with the highest current-day porosity as a starting point to represent the moon's initial porosity in the early stages of the lunar heavy bombardment. They reasoned that older craters that formed in the early stages would have started out highly porous but would have been exposed to further impacts over time that compacted and reduced their initial porosity. In contrast, younger craters, though they formed later on, would have experienced fewer if any subsequent impacts. Their underlying porosity would then be more representative of the moon's initial conditions.

"We use the youngest basin that we have on the moon, that hasn't been subject to too many impacts, and use that as a way to start as initial conditions," Huang explains. "We then use an equation to tune the number of impacts needed to get from that initial porosity to the more compacted, present-day porosity of the oldest basins."

The team studied the 77 craters in chronological order, based on their previously determined ages. For each crater, the team modeled the amount by which the underlying porosity changed compared to the initial porosity represented by the youngest crater. They assumed a bigger change in porosity was associated with a larger number of impacts, and used this correlation to estimate the number of impacts that would have generated each crater's current-day porosity.

These simulations showed a clear trend: At the start of the lunar heavy bombardment, 4.3 billion years ago, the crust was highly porous -- about 20 percent (by comparison, the porosity of pumice is about 60 to 80 percent). Closer to 3.8 billion years ago, the crust became less porous, and remains at its current-day porosity of about 10 percent.

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The beginning of life: The early embryo is in the driver's seat

One often thinks that the early embryo is fragile and needs support. However, at the earliest stages of development, it has the power to feed the future placenta and instructs the uterus so that it can nest. Using 'blastoids', in vitro embryo models formed with stem cells, the Lab of Nicolas Rivron at IMBA showed that the earliest molecular signals that induce placental development and prepare the uterus come from the embryo itself. The findings, now published in Cell Stem Cell, could contribute to a better understanding of human fertility.

Who takes care of whom at the onset of life? The placenta and the uterus nurture and shelter the fetus. But the situation at the very early stage of development, when the blastocyst still floats in the uterus, was unclear so far. Now, the research group of Nicolas Rivron at IMBA (Institute of Molecular Biotechnology of the Austrian Academy of Sciences) uncovered basic principles of early development using blastoids.

Blastoids are in vitro models of the blastocyst, the mammalian embryo in the first few days following fertilization. These embryo models were first developed by the Rivron lab from mouse stem cells (Nature, 2018) and then from human stem cells (Nature, 2021). Blastoids provide an ethical alternative to the use of embryos for research and, importantly, enable multiple discoveries.

Now, blastoids settled a "chicken or egg" dilemma. Using mouse blastoids, the researchers found that the early embryonic part (~10 cells) instructs the future placental part (~100 cells) to form, and the uterine tissues to change. "By doing this, the embryo invests in its own future: it promotes the formation of the tissues that will soon take care of its development. The embryo is in control, instructing the creation of a supporting surrounding," states Nicolas Rivron.

Indeed, the team discovered several molecules secreted by the few cells from which the fetus develops, the epiblasts. They observed that these molecules tell other cells, the trophoblasts that later form the placenta, to self-renew and proliferate, two stem cell properties that are essential for the placenta to grow.

The team also found that these molecules induce the trophoblasts to secrete two other molecules, WNT6 and WNT7B. WNT6 and WNT7B tell the uterus to wrap around the blastocyst. "Other researchers had previously seen that WNT molecules are involved in the uterine reaction. Now we show that these signals are WNT6/7B and that they are produced by the blastocyst trophoblasts to notify the uterus to react. The relevance could be high because we have verified that these two molecules are also expressed by the trophoblasts of the human blastocyst," states Nicolas Rivron.

The team made their findings partly by examining the extent of implantation of the mouse blastoids in an in vivo implantation mouse model. "I was very surprised by the efficiency at which our blastoids implanted into the uterus. And by changing the properties of the trophoblasts within blastoids, including the secretion levels of WNT6/7B, we could clearly change the size of the uterine cocoon," says co-first author Jinwoo Seong, a postdoctoral fellow in the Rivron lab, who performed these experiments.

Because implantation is the bottleneck in human pregnancies -- around 50 percent of pregnancies fail at that time -- and WNT6 and WNT7B are also present in human blastocysts, these findings might explain why, sometimes, things go wrong. "We are currently repeating these experiments with human blastoids and uterine cells, all in a dish, to estimate the conservation of such basic principles of development. These discoveries might ultimately contribute to improving IVF procedures, developing fertility drugs, and contraceptives" says Nicolas Rivron.

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A new giant dinosaur gives insight into why many prehistoric meat-eaters had such tiny arms

A team co-led by University of Minnesota Twin Cities researcher Peter Makovicky and Argentinean colleagues Juan Canale and Sebastian Apesteguía has discovered a new huge, meat-eating dinosaur, dubbed Meraxes gigas. The new dinosaur provides clues about the evolution and biology of dinosaurs such as the Carcharodontosaurus and Tyrannosaurus rex—specifically, why these animals had such big skulls and tiny arms.

The study is published in Current Biology, a peer-reviewed scientific biology journal.

The researchers initially discovered Meraxes in Patagonia in 2012 and have spent the last several years extracting, preparing, and analyzing the specimen. The dinosaur is part of the Carcharodontosauridae family, a group of giant carnivorous theropods that also includes Giganotosaurus, one of the largest known meat-eating dinosaurs and one of the reptilian stars of the recently released “Jurassic World: Dominion” movie.

Though not the largest among carcharodontosaurids, Meraxes was still an imposing animal measuring around 36 feet from snout to tail tip and weighing approximately 9,000 pounds. The researchers recovered the Meraxes from rocks that are around 90-95 million years old, alongside other dinosaurs including several long-necked sauropod specimens.

Meraxes is among the most complete carcharodontosaurid skeleton paleontologists have found yet in the southern hemisphere and includes nearly the entirety of the animal’s skull, hips, and both left and right arms and legs.

“The neat thing is that we found the body plan is surprisingly similar to tyrannosaurs like T. rex,” said Peter Makovicky, one of the principal authors of the study and a professor in the University of Minnesota N.H. Winchell School of Earth and Environmental Sciences. “But, they’re not particularly closely related to T. rex. They're from very different branches of the meat-eating dinosaur family tree. So, having this new discovery allowed us to probe the question of, ‘Why do these meat-eating dinosaurs get so big and have these dinky little arms?’”

“The discovery of this new carcharodontosaurid, the most complete up to now, gives us an outstanding opportunity to learn about their systematics, paleobiology, and true size like never before,” said Sebastian Apesteguía, a co-author of the study and a researcher at Maimónides University in Argentina.

With the statistical data that Meraxes provided, the researchers found that large, mega-predatory dinosaurs in all three families of therapods grew in similar ways. As they evolved, their skulls grew larger and their arms progressively shortened.

The possible uses of the tiny forelimbs in T. rex and other large carnivorous dinosaurs have been the topic of much speculation and debate.

“What we’re suggesting is that there’s a different take on this,” Makovicky said. “We shouldn’t worry so much about what the arms are being used for, because the arms are actually being reduced as a consequence of the skulls becoming massive. Whatever the arms may or may not have been used for, they’re taking on a secondary function since the skull is being optimized to handle larger prey.”

The researchers also found that carcharodontosaurids including species from Patagonia evolved very quickly, but then disappeared suddenly from the fossil record very soon after.

“Usually when animals are on the verge of extinction, it’s because they’re evolutionary rates are quite slow, meaning they aren’t adapting very quickly to their environment,” explained  Juan Canale, the study’s lead author and a researcher at the National University of Río Negro. “Here, we have evidence that Meraxes and its relatives were evolving quite fast and yet within a few million years of being around, they disappeared, and we don’t know why. It’s one of these finds where you answer some questions, but it generates more questions for the future.”

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How sound reduces pain in mice

An international team of scientists has identified the neural mechanisms through which sound blunts pain in mice. The findings, which could inform development of safer methods to treat pain, were published in Science. The study was led by researchers at the National Institute of Dental and Craniofacial Research (NIDCR); the University of Science and Technology of China, Hefei; and Anhui Medical University, Hefei, China. NIDCR is part of the National Institutes of Health.

"We need more effective methods of managing acute and chronic pain, and that starts with gaining a better understanding of the basic neural processes that regulate pain," said NIDCR Director Rena D'Souza, D.D.S., Ph.D. "By uncovering the circuitry that mediates the pain-reducing effects of sound in mice, this study adds critical knowledge that could ultimately inform new approaches for pain therapy."

Dating back to 1960, studies in humans have shown that music and other kinds of sound can help alleviate acute and chronic pain, including pain from dental and medical surgery, labor and delivery, and cancer. However, how the brain produces this pain reduction, or analgesia, was less clear.

"Human brain imaging studies have implicated certain areas of the brain in music-induced analgesia, but these are only associations," said co-senior author Yuanyuan (Kevin) Liu, Ph.D., a Stadtman tenure-track investigator at NIDCR. "In animals, we can more fully explore and manipulate the circuitry to identify the neural substrates involved."

The researchers first exposed mice with inflamed paws to three types of sound: a pleasant piece of classical music, an unpleasant rearrangement of the same piece, and white noise. Surprisingly, all three types of sound, when played at a low intensity relative to background noise (about the level of a whisper) reduced pain sensitivity in the mice. Higher intensities of the same sounds had no effect on animals' pain responses.

"We were really surprised that the intensity of sound, and not the category or perceived pleasantness of sound would matter," Liu said.

To explore the brain circuitry underlying this effect, the researchers used non-infectious viruses coupled with fluorescent proteins to trace connections between brain regions. They identified a route from the auditory cortex, which receives and processes information about sound, to the thalamus, which acts as a relay station for sensory signals, including pain, from the body. In freely moving mice, low-intensity white noise reduced the activity of neurons at the receiving end of the pathway in the thalamus.

In the absence of sound, suppressing the pathway with light- and small molecule-based techniques mimicked the pain-blunting effects of low-intensity noise, while turning on the pathway restored animals' sensitivity to pain.

Liu said it is unclear if similar brain processes are involved in humans, or whether other aspects of sound, such as its perceived harmony or pleasantness, are important for human pain relief.

"We don't know if human music means anything to rodents, but it has many different meanings to humans -- you have a lot of emotional components," he said.

The results could give scientists a starting point for studies to determine whether the animal findings apply to humans, and ultimately could inform development of safer alternatives to opioids for treating pain.

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8000 kilometers per second: Star with the shortest orbital period around black hole discovered

Researchers at the University of Cologne and Masaryk University in Brno (Czech Republic) have discovered the fastest known star, which travels around a black hole in record time. The star, S4716, orbits Sagittarius A*, the black hole in the centre of our Milky Way, in four years and reaches a speed of around 8000 kilometres per second. S4716 comes as close as 100 AU (astronomical unit) to the black hole -- a small distance by astronomical standards. One AU corresponds to 149,597,870 kilometres. The study has been published in The Astrophysical Journal.

In the vicinity of the black hole at the centre of our galaxy is a densely packed cluster of stars. This cluster, called S cluster, is home to well over a hundred stars that differ in their brightness and mass. S stars move particularly fast. 'One prominent member, S2, behaves like a large person sitting in front of you in a movie theatre: it blocks your view of what's important,' said Dr Florian Peissker, lead author of the new study. 'The view into the centre of our galaxy is therefore often obscured by S2. However, in brief moments we can observe the surroundings of the central black hole.'

By means of continuously refining methods of analysis, together with observations covering almost twenty years, the scientist now identified without a doubt a star that travels around the central supermassive black hole in just four years. A total of five telescopes observed the star, with four of these five being combined into one large telescope to allow even more accurate and detailed observations. 'For a star to be in a stable orbit so close and fast in the vicinity of a supermassive black hole was completely unexpected and marks the limit that can be observed with traditional telescopes,' said Peissker.

Moreover, the discovery sheds new light on the origin and evolution of the orbit of fast-moving stars in the heart of the Milky Way. 'The short-period, compact orbit of S4716 is quite puzzling,' Michael Zajaček, an astrophysicist at Masaryk University in Brno who was involved in the study, said. 'Stars cannot form so easily near the black hole. S4716 had to move inwards, for example by approaching other stars and objects in the S cluster, which caused its orbit to shrink significantly,' he added.

From Science Daily

Volcano's eruption will help scientists plot weather, climate

As it captivated people around the world, the January eruption of the Hunga Tonga-Hunga Ha'apai volcano gave scientists a once-in-a-lifetime chance to study how the atmosphere works, unlocking keys to better predict the weather and changing climate.

The volcano, located in the South Pacific nation of Tonga, became active Dec. 20, 2021, and erupted Jan. 15, 2022. The blast obliterated one of the country's many islands and was described by NASA as more powerful than an atomic bomb.

UMass Lowell's Mathew Barlow, professor of environmental, earth and atmospheric sciences, was among an international team of scientists who studied the atmospheric response to the eruption, the likes of which has never before been recorded. The group's findings were published in Nature.

As part of his work, Barlow created an animated video from satellite data that shows the eruption's dramatic effects. The event saw atmospheric waves pulse around the globe several times and stretch from Earth to the edge of space, some at speeds of 720 mph. The eruption also shot a plume of water vapor, along with volcanic ash, soil and smoke, 31 miles into the air. A short video produced by the researchers summarizes the effects.

"Some of the wave types the Hunga Tonga generated are very important to understanding how the atmosphere works and our ability to make effective computer models for weather forecasting and climate projections," said Barlow, a faculty member in UMass Lowell's Climate Change Initiative. "Through the expulsion of particles into the high atmosphere, some strong eruptions can also have a cooling effect on the climate, though the amount produced by Hunga Tonga does not appear sufficient for a notable climate effect, unlike other volcanic eruptions over the last century, like the Pinatubo eruption in Alaska in 1991."

According to Barlow, the Hunga Tonga explosion appears to be the strongest single burst of volcanic energy released in 140 years, since the eruption of the Krakatoa volcano in Indonesia in 1883. Coupled with advances in satellite imagery, the strength of the Hunga Tonga eruption gave scientists an unprecedented view of atmospheric waves. Barlow said he and fellow researchers were able to analyze its effects in near-real time communication with agencies across the globe.

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